This invention pertains generally to apparatus for transporting magnetic tape during the recording and playback of signals thereon, and more particularly to transport apparatus of the type in which a drive capstan engages supply and take-up rolls in peripheral driving relationship.
In tape transport apparatus of this type, it is important from the standpoint of tape control to maintain a proper force differential whereby the take-up roll is pressed against the drive capstan with a greater force than the supply roll. One method of providing the desired force differential is to resist movement of the take-up roll away from the capstan as tape is transferred to that roll while permitting the supply roll to move freely toward the capstan. In order to prevent loss of control of the tape it is essential that this force differential be established immediately when tape movement begins, and that it be reversed immediately when the direction of tape movement is reversed, so as to apply he greater force to the new take-up roll as quickly as possible.